Insoles and inserts for shoes have long been popular to increase the comfort level of the shoe wearer. They are primarily designed to cushion or provide additional support for the foot for both medical and non-medical reasons. A fairly recent innovation in shoe inserts is the use of liquid or gel-filled cavities within the insert to provide an adaptive, form-fitting cushion and a more even distribution of force onto the sole of the foot.
This typically involves having a pouch of the liquid or gel within the insert which allows the substance inside to move freely about inside the insert, thus conforming to the shape of the foot. Problems arise with this type of insert construction as it is possible for all the liquid or gel to pool in a single location, thereby negating the benefits of the force-distributive properties of the liquid or gel.
Another innovation to come to footwear is that of temperature control within the shoe. Most common is the use of heat production in a shoe insert. Though there are some employing electrical means of heat production, the most common form is the use of exothermic chemical reactions which provide a steady, relatively long-duration source of heat.
The second, less common form of temperature control within the shoe is by means of decreasing the temperature. Like heated inserts, there are examples that use electrically powered means of cooling the shoe, but there is no prior art employing an endothermic chemical reaction to serve this purpose.
The electrically powered means of temperature in both cases are impractical for everyday use as the effort required to maintain the desired temperature with such devices exceeds the perceived benefit of the devices, hence their failure to gain a position within the shoe insole market.